- must require medication (e.g., non-opioids or opioids up to an equivalent dose of 160 mg oral morphine/day) for the treatment of pain due to DPN for at least 1 month prior to Visit 1 and must be dissatisfied with the current treatment (in terms of efficacy and/or tolerability). Medication for the treatment of pain due to DPN should be required on at least 4 of 7 consecutive days.